Hi,
I understand your consern and you have a good point.
About the replacement cartridges, if you got a replacement printer, that printer should have come with a new set of setup ink cartridges, so there is no money expence from your side.
If the defective printer had a set of cartridges that your purchased, call HP and inform that, is posible provide the POP of the purchase of those cartridges so you can get your ink back.
Best regards